Fluoroalkylation of polyester by end-capped fluoroalkyl-functional silanes

The surface modification of polyester was examined using both monomeric and oligomeric silanes having end-capped fluoroalkyl groups. From contact angle measurements, the surface foe energies of polyester were reduced to 15-20 mJ/m(2) for the dispersive component and 1-3 mJ/m(2) for the polar component, respectively, and all the surfaces were shown to be both highly water-and oil-repellent. fly XPS (X-ray photoelectron spectroscopy) measurements, using the C Is peak attributable to the C=0 of polyester, the thickness of the siloxane layer on the surface was shown to be less than 5 nm. The solvent durability (resistance) of the modified surfaces was evaluated using contact angle and XPS measurements. Although all the modified surfaces showed durability against dodecane, xylene, ethyl acetate, tetrachloroethylene, and hydrochloric acid, long-time immersion in fluorine-containing solvents reduced the oil repellency of some of the surfaces modified with monomeric or oligomeric silanes having short fluoroalkyls. In particular, immersion in alkaline solution destroyed the siloxane network and thus reduced their water repellency, while interestingly their oil repellency remained unchanged, The modification mechanism is also discussed in terms of simultaneous thermal anchoring and polymerization of silanes.